fix: Vite dev server 配置 API 代理，解决 405 Method Not Allowed

ai_knowledge_base_v2/apps/user-client/vite.config.ts

@@ -5,5 +5,11 @@ export default defineConfig({
   plugins: [vue()],
   server: {
     port: 5173,
+    proxy: {
+      "/api": {
+        target: "http://backend:8100",
+        changeOrigin: true,
+      },
+    },
   },
 });